Firefighters were called to a tent fire in Catterick Garrison on Thursday evening.
A crew from Richmond responded to the incident at about 6.52pm.
North Yorkshire Fire and Rescue Service said the fire measured approximately five metres by five metres.
Action had already been taken to deal with the blaze before firefighters arrived and the crew carried out an inspection of the scene.
The fire service said the cause of the blaze was believed to have been deliberate.
